Process for manufacture of hard mineral fiber slabs with coating

ABSTRACT

This disclosure teaches a method of manufacturing hard mineral fiber slabs with a surface finish produced from paper impregnated by a spirit solution of phenolformaldehydrate resin, adding at the same time a spirit solution of stearine and a water-spirit solution of hexamethylenetetramine together with a wetting agent. The paper is pressed onto a carpet made of mineral fibers impregnated by resin.

United States Patent Milsimer et a].

[451 Mar. 28, 1972 PROCESS FOR MANUFACTURE OF HARD MINERAL FIBER SLABS WITH COATING Frantlsek Milsimer; Jlri Zampach, both of Prague, Czechoslovakia Assignee: World Patent Development Corp.

Filed: Nov. 24, 1969 Appl. No.: 879,265

Inventors:

Foreign Application Priority Data Nov. 26, 1968 Czechoslovakia ..8072l68 US. Cl ..l56/62.4, 117/155 L, 156/167,

156/335,161/413,162/165 Int. Cl. ..B29j 5/00 Field 01 Search ..117/102 R, 155 L; l56/62.4,

[56] References Cited FOREIGN PATENTS OR APPLICATIONS 954,527 4/1964 Great Britain .1 156/62.4

Primary Examiner-Leland A. Sebastian Attorney-Charles E. Baxley, Frank M, Nolan and Thomas E. Tate [5 7] ABSTRACT This disclosure teaches a method of manufacturing hard mineral fiber slabs with a surface finish produced from paper impregnated by a spirit solution of phenolformaldehydrate resin, adding at the same time a spirit solution of stearine and a water-spirit solution of hexamethylenetetramine together with a wetting agent. The paper is pressed onto a carpet made of mineral fibers impregnated by resin.

2 Claims, 7 Drawing Figures PATENTEDHAREB 1912 SHEET 1 OF 2 FIG.

9 2 3 m Mm W WQH 0m Jw 4/ 3 m m am m I r 5 m G 4 H 79 7 7 7 7 2 H wfimwm ws K (K W w UAT PROCESS FOR MANUFACTURE OF HARD MINERAL FIBER SLABS WITH COATING The object of this invention is to manufacture hard slabs from mineral fibers, bound together by synthetic resin, and with surface finishes consisting of papers pressed thereon. The papers are impregnated with a decorative print by a phenolformaldehydrate resin, which resin is prepared from a condensed product of phenol and formaldehydrate in an acid environment in a spirit solution adding at the same time hexamethylenetetramine as a hardening agent and also stearine to inhibit adhesion along with a wetting agent.

In the prior art, binders for mineral fibers used for fabrication of hard slabs were cement, for example asbestos fibers were bound by cement to produce hard slabs. Furthermore, mineral fibers made from blast furnace slag have been treated in a wet process on machines similar to those used in paper making, with the binder being sulfate cellulose.

On both these prior art slabs it has been unworkable to press papers which are impregnated by synthetic resins. Another disadvantage is that there is a shortage of asbestos fibers. Manufacture of slabs from blast furnace slag and sulfate cellulose has a disadvantage in that the slabs get damp and swell in a moist environment. The foregoing disadvantages are avoided by manufacturing hard slabs according to this inventron.

DRAWINGS The foregoing and other advantages will appear more fully from the accompanying drawings wherein:

FIG. 1 is a schematic representation of the method of making mineral fiber slabs according to this invention.

FIG. 2 is an idealized section taken along line 22 of FIG. 1 to illustrate formation of fibers from molten slag by spinning the slag about wheels of progressively greater angular velocity.

FIG. 3 depicts progressively the change in shape of the mineral fibers as they advance from roller to roller in FIG. 2.

FIG. 4 shows a blanket of mineral fibers with paper applied to both faces thereof.

F 16. 5 indicates pressing of mineral fiber blankets between sheets of polished stainless steel.

FIG. 6 demonstrates relationships of strength to density for slabs produced in accordance with this invention.

FIG. 7 offers a comparison of slag and glass on a strength to diameter basis.

As best seen in FIG. 1, molten slag 11 is tapped from furnace 12 and is delivered to fiber-making equipment generally designated 13 wherein the slag is spun in turn about wheels 14, 16, 17 and 18 (see FIG. 2) which rotate respectively in the directions indicated at progressively higher angular velocities whereby, as shown in FIG. 3, drops of slag 19 are formed progressively by kinetic influences through stages 21 and 22 to become long fibers 23 preferably with thicknesses from 5 to 7 microns. As shown in FIG. 1, fibers 23 are delivered by air stream 24 into settling chamber 26 which is provided at its bottom with endless belt 27 having vacuum chest 28 therebeneath so that the fibers settle on belt 27 to form a continuous carpet 29 of fibers. F rom settling chamber 26, carpet 29 is passed between rollers 31 for compaction and impregnation thereof by a water solution of phenolformaldehydrate resin delivered from reservoir 32. Vacuum chest 33 draws the resin into carpet blanket 29. Excess resin is collected and returned to reservoir 32 via line 34. In this manner the carpet is impregnated evenly by to percent resin (on a dry weight basis). Thereafter carpet 29 is. further compressed between rollers 36, has papers 37 applied to it and is cut by shears 38 into convenient lengths. A fiber blanket 29 with papers 37 applied to the top and bottom thereof is shown in FIG. 4. Blankets 29, with papers 37 applied thereto, are shown stacked, with highly polished stainless steel plates 39 interposed therebetween, in a press for further compaction thereof and for thermal setting.

For manufacture of mineral fibers a wide variety of minerals can be used. including blast-furnace slag which is a waste product in metallurgical industry. In considering the suitability of the mineral to be used, it is necessary to determine its melting point, degree of acidity and if necessary the additive elements that may be required. Tests can be made by means of an electrically heated graphite crucible. In this way the melting temperature as well as the temperature of the fiber can be determined. Fibers thus tested enable one to evaluate their mechanical properties such as tensile strength, brittleness, relaxation, etc. It is essential in this process, that the modulus of acidity be at least 1.2, i.e.,

Si 0 +Al O /CaO +M,O 1.2

This modulus of acidity affords an index of mechanical strength as well as chemical and heat stability of the mineral fibers. Heat resistance is raised by increasing the contents of M 0 and SiO For instance, when 30% M 0 is in the charge, the heat resistance of fibers is 800 C. By suitable additives (for example brick or ceramic fragments) this modulus of acidity can be adjusted. Similarly, should the melting temperature of the mineral be too high, it can be decreased by using suitable additives. The most satisfactory melting temperature is between 1,300 and 1,400 C. High melting temperature causes increased costs in the fiber manufacture.

When choosing the type of melting furnace 12, it is necessary to take into account local sources of electric energy or other power and their costs.

A number of proven methods are known for manufacture of fibers from melted materials. To achieve a reliable output of the individual methods of manufacture it is necessary to keep constant viscosity of the melted material which comes onto the fiber-making equipment 13. Due to the fact that the functional dependence between the viscosity of the melted metal and its temperature is a logarithmic one, it is necessary, first of all, to keep the melting temperature constant. This melted metal comes onto first fiber making wheel 14, where it is divided into single drops which are then drawn by kinetic energy into fibers. When manufacturing hard slabs it is necessary for the fiber to belong and its thickness within the range of 5 to 7 microns.

In fiber making a certain part of the melted material always remains in drops or small globules unevenly dispersed among the fibers. These particles are called granulates and detract from mechanical properties of the final product. It is essential to keep these granulates within the range of:

over 0.l5 mm. diameter max. 15% 0.25 mm. diameter max. 7%

0.50 mm. diameter max. 3%

Mineral fiber carpet 29 impregnated by phenolformaldehydrate resin has paper foil 37 (impregnated by resin) applied thereto. A decorative paper imprinted with wood design can be used as paper 37. In some cases, in order to gain a thicker layer of gloss, a basic paper can be used underneath the decorative paper.

The resin in the foil 37 comprises the following:

50 weight parts powder phenolformaldehydrate resin with 10 percent hexamethylenetetramine content 50 weight parts ethanol (denaturated 2 percent toluene) 1.5 weight parts hexamethylenetetramine 1.5 weight parts distilled water 0.4 weight parts stearine 0.05 weight parts Alfonal K (the product obtained by condensing fat acids of coconut oil with diethanolamine) Preparation of resin solution for the foil from its individual components is as follows:

a. 50 kg. of phenolformaldehydrate resin with 10 percent hexamethylenetetramine is dissolved in 46 kg. of methylated spirit,

b. the spirit solution of stearine is added (this solution is prepared by dissolving 0.4 kg. stearine in 1 kg. of spirit at a temperature of 60 C.) and the mixture is stirred until a clear solution is formed,

c. gradually (with continuo tion of hexamethylenetetramine together with Alfonal K is added (this solution is prepared by dissolving first 1.5 kg. of hexamethylenetetramine in 1.5 kg. of hot water of 70 to 80 C. into which 0.05 kg. of Alfonal K has been adde g" d. then everything is diluted by 3 kg. of methylated spirit which is added gradually until a clear solution is achieved. This procedure should be followed carefully to avoid precipitation of either resin, stearine or hexamethylenetetramine. Due to the fact that the solubility of the hexamethylenetetramine in spirit is limited, a further amount of hexamethylenetetramine is added in the form of a waterspirit solution, and in order that stearine does not precipitate from'the solution, the wetting agent Alfonal K is added. The resin solution impregnates the paper with any print on it in us stirring) the water-spirit soluconventional impregnating equipment, drying it at the same a time at a temperature 'of 110 C. until the solvents are completely evaporated. Hexamethylenetetramine acts as a speedy hardening element, thus preventing formation of surface deformations, while the stearine acts as an antiadhesion agent which diffuses during hot pressing into the surface between the sheet and the papers, forming thus a safety coat: i.e., a film which hinders the paper from sticking to the stainless steel.

Mineral fiber carpet 29 covered with papers 37 from both sides is placed between stainless steel sheets 39 about 4 mm. thick. The sides of stainless steel sheets 39 in contact with the foil, should be ground and polished to have a high luster. Their surfaces must be without any defects, in order to obtain perfect surfaces for the pressed slabs.

It is advantageous to use a multi-stage press. The plurality of stages enables one to change capacity to a large extent. The' most suitable press is one with six to stages. Pressing time is 25 to minutes, and is dependent on the thickness and specific weight of the slab because the fibers act as heat insulation. Heating of the mineral fiber carpet must be thorough so that the binding resin gets hardened across the whole cross section. The paper itself is hardened in 5 minutes at 160 C. The advantages of using the foil and this process of hardening is that when hardening has been completed it is not necessary to cool the stages of the press to take out the pressed slabs at a temperature of 20 C. as must be done when a melamineformaldehydrate resin is used. The present method cuts pressing time in half and saves almost 70 percent of the calories need for heating of the press.

For evaluation of the process, four slabs with various volume weights were tested and relations between mechanical properties and slab densities were determined.

Modulus of elasticity Bending strength Tensile strength Specific weight When strained, the material behaves as a brittle one. Up to fracture, the functional dependence of the stress deformation is linear and the deformation limit in tensile strength in 0.1 to 0.2 percent, and in compression 0.1 to 0.5 percent.

A survey of the values of mechanical properties is shown in FIG. 6. From FIG. 6 it can be seen that most of the mechanical properties ascend and that the culminating point is reached with the volume weight of 1,500 kg./m.". This also well shows that it is essential to consider which mechanical stresses will afiect the slab to be made before the system for theirmanufacture has been finalized. According to FIG. 6 it may be possible to decrease the density of a slab as much as by 30 percent and keep at the same time its mechanical strength. By decreasing the weight the price of the slab is lowered.

FIG. 7 shows a comparison between a glass and a slag fiber, as regards their tensile strength. From the graph it can be seen that the strength of slag fibers in comparison with glass fibers is about 50 percent. Due to the fact that one only utilizes 50 percent of the glass fiber strength in glass laminates (which have great tensile strength) one can well presume that by using the slag fiber strength to its full extent one may achieve the same overall effectiveness as glass fiber slabs. For this purpose it will be necessary to use resins with lower moduli of elasticity. Such resins will enable the stress to be evenly spread on individual fibers and thus fully utilize the strength of the fibers.

We claim:

1. A method for treating a paper to be pressed and comprising impregnating the paper by a solution of phenolformaldehydrate resin along with stearine and hexamythylenetetramine as well as a wetting agent, the wetting agent being a product obtained by condensing fat acids of I coconut oil with diethanolamine.

2. A method for manufacturing slabs from minerals and comprising in combination:

forming the minerals into relatively long thin fibers, arranging the fibers in a blanket impregnated by a resin, impregnating a paper by a spirit solution of phenolformaldehydrate resin adding at the same time a spirit solution of stearine and a water-spirit solution of hexamethylenetetramine and a wetting agent with the wetting agent being a product obtained by condensing fat acids of coconut oil with diethanolamine, pressing the paper to the blanket at superambient temperature.

* k I! I! t 

2. A method for manufacturing slabs from minerals and comprising in combination: forming the minerals into relatively long thin fibers, arranging the fibers in a blanket impregnated by a resin, impregnating a paper by a spirit solution of phenolformaldehydrate resin adding at the same time a spirit solution of stearine and a water-spirit solution of hexamethylenetetramine and a wetting agent with the wetting agent being a product obtained by condensing fat acids of coconut oil with diethanolamine, pressing the paper to the blanket at superambient temperature. 